Slime control compositions containing phenolic compounds and their use

ABSTRACT

THE PRESENT INVENTION RELATES TO CERTAIN PROCESSES AND COMPOSITIONS USEFUL FOR INHIBITING AND/OR CONTROLLING THE GROWTH OF SLIME IN WATER AND, IN PARTICULAR, WATER EMPLOYED FOR INDUSTRIAL PURPOSES. WATER EMPLOYED IN THE MANUFACTURE OF PULP PAPER AND WATER EMPLOYED IN COOLING WATER SYSTEMS, AS WELL AS OTHER INDUSTRIAL WATERS, PROVIDE ENVIRONMENTS WHICH ARE CONDUCTIVE TO SLIM FORMATION. THE NOVEL COMPOSITION OF THE PRESENT INVENTION ARE MIXTURES WHICH SHOW UNEXPECTED SYNERGISTIC ACTIVITY AGAINST MICROORAGANISMS, INCLUDING BACTERIA, FUNGI AND ALGAE, WHICH PRODUCE SLIME IN AQUEOUS SYSTEMS. THE SLIME, OF COURSE, IS OBJECTIONABLE FROM AN OPERATIONAL AND /OR AN AESTHETIC POINT OF VIEW. SPECIFICALLY, THE INVENTION IS DIRECTED TO AND THE USE OF COMPOSITIONS COMPRISING A COMBINATION OF 5-CHLORO-4-PHENYL - 12, - DITHIOLE-3-/NE AND PHENOLIC COMPOUNDS (OR MIXTURES THEREOF). THE INVENTIVE COMPOSITIONS INHIBIT THE GROWTH OF SLIME IN WATER, OR MORE SPECIFICALLY, POSSESS BIOCIDAL ACTIVITY AGAINST BACTERIA, FUNGI AND/OR ALGAE. THE PHENOLIC COMPOUNDS CONTMPLATE FOR USE IN ACCORDANCE WITH THE PRESENT INVENTION ARE THOSE PHENOLIC COMPOUNDS WHICH POSSESS THE CAPACITY TO KILL OR INHIBIT THE GROWTH OF SLIME-FORMING MICROORGANISMS SUCH AS BACTERIA, FUNGI AND ALGAE. THE TYPE PHENOLIC COMPOUNDS ENCOMPASSED BY THE PRESENT INVENTION MAY KBE EXAMPLIFIED BY: PHENOL, ORTHO-PHENYLPHENOL, 2,3,4,6TETRACHLOROPHENOL, 4-CHLORO - 2 - CYCLOPENTYLPHENOL AND 2-CHLORO-4-PHENYLPHENOL.

Patented Aug. 13, 1974 3,829,305 SLllVIE CONTROL COMPOSITIONS CONTAININGPHENOLIC COMPOUNDS AND THEIR USE Robert H. Brink, Jr., Doylestown,Bernard F. Shema, Glenside, Roger L. Justice, Cornwells Heights and PaulSwered, Philadelphia, Pa., assignors to Betz Laboratories, Inc.,Trevose, Pa. No Drawing. Filed July 6, 1971, Ser. No. 160,191

Int. Cl.: A01n 9/02 US. C]. 71-67 9 Claims ABSTRACT OF THE DISCLOSUREThe present invention relates to certain processes and compositionsuseful for inhibiting and/or controlling the growth of slime in waterand, in particular, water employed for industrial purposes. Wateremployed in the manufacture of pulp paper and water employed in coolingwater systems, as well as other industrial waters, provide environmentswhich are conducive to slime formation. The novel compositions of thepresent invention are mixtures which show unexpected synergisticactivity against microorganisms, including bacteria, fungi and algae,which produce slime in aqueous systems. The slime, of course, isobjectionable from an operational and/or an aesthetic point of view.Specifically, the invention is directed to and the use of compositionscomprising a combination of S-chloro 4 phenyl 1,2 dithiole-3-one andphenolic compounds (or mixtures thereof). The inventive compositionsinhibit the growth of slime in water, or more specifically, possessbiocidal activity against bacteria, fungi and/or algae. The phenoliccompounds contemplated for use in accordance with the present inventionare those phenolic compounds which possess the capacity to kill orinhibit the growth of slime-forming microorganisms such as bacteria,fungi and algae. The type phenolic compounds encompassed by the presentinvention may be exemplified by: phenol, ortho-phenylphenol, 2,3,4,6-tetrachlorophenol, 4-chloro 2 cyclopentylphenol and2-chloro-4-phenylphenol.

BACKGROUND OF THE INVENTION The formation of slime by microorganisms isa problem which attends many systems. For example, lagoons, lakes,ponds, pools and such systems as cooling water systems and pulp andpaper mill systems all possess conditions which are conducive to thegrowth and reproduction of slime-forming microorganisms. In bothonce-through and recirculating cooling systems, for example, whichemploy large quantities of water as a cooling medium, the formation ofslime by microorganisms is an extensive and constant problem.

Airborne organisms are readily entrained in the water from coolingtowers and find this warm medium and ideal environment for growth andmultiplication. Aerobic and heliotropic organisms fluorish on the towerproper while other organisms colonize and grow in such areas as thetower sump and the piping and passages of the cooling system. Such slimeserves to deteriorate the tower structure in the case of Wooden towers.In addition, the deposition of slime on metal surfaces promotescorrosion. Furthermore, slime carried through the cooling system plugsand fouls lines, valves, strainers, etc. and deposits on heat exchangesurfaces. In the latter case, the impedance of heat transfer can greatlyreduce the efliciency of the cooling system.

In pulp and paper mill systems, slime formed by micro organisms is alsofrequently and, in fact, commonly encountered. Fouling or plugging byslime also occurs in the case of pulp and paper mill systems. Of greatersignificance, the slime becomes entrained in the paper produced to causebreakouts on the paper machines with consequent work stoppages and theloss of production time or unslightly blemishes in the final product;this, of course, results in rejects and wasted output. The previouslydiscussed problems have resulted in the extensive utilization ofbiocides in cooling water and pulp and paper mill systems. Materialswhich have enjoyed widespread use in such applications include chlorine,organo-mercurials, chlorinated phenols, organo-bromines, and variousorgano-sulfur compounds. All of these compounds are generally useful forthis purpose but each is attended by a variety of impediments. Forexample, chlorination is limited both by its specific toxicity forslime-forming organisms at economic levels and by the ability ofchlorine to react which results in the expenditure of the chlorinebefore its full biocidal function may be achieved. Other biocides areattended by high costs, odor problems and hazards in respect to storage,use or handling which limit their utility. To date, no one compound ortype of compound has achieved a clearly established predominance inrespect to the applications discussed. Likewise, lagoons, ponds, lakesand even pools, either used for pleasure purposes or used for industrialpurposes for the disposal and storage of industrial wastes become,during the warm weather, besieged by slime due to microorganism growthand reproduction. In the case of the recreational areas, the problem ofinfection, odor, etc. is obvious. In the case of industrial storage ordisposal of industrial materials, the microorganisms cause additionalproblems which must be eliminated prior to the materials use or thewaste is treated for disposal.

It is the object of the present invention to provide compositions forcontrolling slime-forming microorganisms in aqueous systems, such ascooling water systems and pulp and paper mill systems, and forcontrolling slime formation or microorganism populations in aqueousbodies in general. Moreover, another object of the invention is theprovision of methods for preserving materials and for controllingslime-forming microorganisms in any aqueous system which is conducive tothe growth and reproduction of microorganisms and, in particular,cooling water and paper and pulp mill systems. These methods employ acombination of 5-chloro-4-phenyl-1,2-dithiole-3-one and a phenoliccompound (or mixtures thereof). The phenolic compound must possess theproperty of being biocidally active against bacteria, fungi and/oralgae, i.e. either kill or inhibit the growth of these microorganisms.

In the practice of the invention, the combination is added to theparticular material to be preserved or to the system being treated, forexample cooling water systems, paper and pulp mill systems, pools,ponds, lagoons, lakes, etc., in a quantity adequate to control theslime-forming microorganisms which are contained by, or which may becomeentrained in, the system which is treated. It has been found that suchcompositions and methods control the growth and occurrence of suchmicroorganisms as may populate these particular systems.

GENERAL DESCRIPTION OF THE INVENTION As earlier stated, the inventivecompositions comprise a combination of5-chloro-4-phenyl-1,2-dithiole-3-one and a particular phenolic compound(or mixtures thereof) with either compound being present in such aquantity as to impart a synergistic behavior for the purpose of thecomposition as a whole. Preferably, the compositions contain apercentage by weight ranging from about 5 to about of the dithiole-3-onecompound and from about 5 to about 95% of the phenolic compound. Whenthese two ingredients are mixed either beforehand or by addition to theaqueous system individually, the resulting mixtures possess a highdegree of slimicidal activity which could not have been predictedbeforehand from the known activity of the individual ingredientscomprising the mixture. Accordingly, it is therefore possible to producea more effective slime-control agent than has previously been available.Because of the enhanced activity of the mixture, the total quantity ofbiocide required for an effective treatment may be reduced. In addition,the high degree of biocidal efiectiveness which is provided by each ofthe ingredients may be exploited without use of the higherconcentrations of each. This feature is not only important andadvantageous from an economical point of view, but also most desirablefrom the pollution or ecological standpoints. In this regard, it mightbe pointed out that the smaller the amount of a chemical that isrequired for effective treatment, the smaller the problem in treatingthe wastes from these systems. In both cooling water systems and inpaper and pulp mill systems, certain discharge of waste water, e.g.blowdown in cooling water systems, is a necessity. However, because ofthe current concern and legislation regarding the discharge of wastes,the efiluent waste water must be treated to reduce and, hopefully, toeliminate any undesirable constituents. This treatment, of course, istime consuming and costly. Accordingly, a reduction in additive usagewill result in a corresponding reduction in costs for the treatment ofwastes containing these additives.

To demonstrate the synergism which is obtainable from the combination ofthe phenolic compounds with the ehloro-4-phenyl-1,2-dithiole-3-one(supplied by Hercules Corporation under designation S1612), variousexemplary phenolic compounds were chosen. As earlier indicated,synergistic activity can be obtained by combining the dithiole-3-onecompound with phenolic compounds which exhibit growth inhibitory orbiocidal activity with respect to bacteria, fungi and/or algae. Thephenolic compounds which were chosen as representative are as follows:phenol, ortho-phenylphenol (Dow Chemical Company Dowicide 1);2-chloro-4-phenylphenol (Dowicide 4); 2,3,4,6-tetrachlorophenol(Dowicide 6); and 4- chloro-12-cyclopentylphenol.

In order to illustrate the synergistic activity, the efficacy and thecomparative effectiveness of the inventive compositions, various testswere utilized and will be described following.

SPECIFIC EMBODIMENTS Example 1 Synergistic combination:

Compound A: 5-chloro-4-phenyl-1,2-dithiole-3-one Compound B: Phenol Thecompositions of this Example contained S-chloro- 4-phenyl-1,2dithiole-3-one (referred to as Compound A in the Test Equations and inTables 1 through 1C) and phenol (referred to as Compound B in thisExample and in the Test Equations and in Tables 1 through 1C) in theweight ratios expressed in the Tables which follow. The compositionswere tested for synergistic activity in accordance with the methoddescribed. The synergism test was utilized to evaluate each of thecombinations of this Example and the following Examples.

Synergistic Index Test.'Synergistic activity was demonstrated by addingCompound A and Compound B in varying ratios and over a range ofconcentrations to liquid nutrient medium which was subsequentlyinoculated with a standard volume of suspension of the bacteriumAerobacter aerogenes. Following two days incubation, the lowestconcentration of each ratio which prevented growth of the bacteria wastaken as the end point.

Growth or no-growth was determined by turbidity or clarity respectivelyin the medium. End points for the various mixtures were then comparedwith end points for the pure active ingredients working alone inconcomitantly prepared culture bottles. Synergism was determined by themethod described by Kull et a1. [F. C. Kull, P. C.

Eisman, H. D. Sylwestrowicz and R. L. Mayer, Applied Microbiology, 9,538-41 (1961)] and the relationships,

Q, B =1 1s additivit Q. Q.. y

1 is antagonism 1 is synergism where,

For mixtures of Compounds A and B, and for Compound A and Compound Bacting alone, the following results were observed:

TABLE 1 Quantities producing end points (p.p.m.) QA Qn Weight ratio of Ato B Qx QB Mixture QA/Qa QB/Qb Q Qb 0. 55 11. 0 0. 747 0. 0003 O 75 10.0 20. O 0. 714: 0. 005 0. 72 171 180 0. 643 0. 086 O. 73 0/10 2,000

It is evident from the data recorded in Table 1 that compositions of thepresent invention function to control slime growth due to microorganismsnot only at equal portions of the respective ingredients, but also wherejust minor amounts of one or the other are present. This discovery ofsynergism at the lower levels is extremely valuable since it illustratesconclusively that the ingredients are compatible over the widepercentage by weight range.

Bactericidal effectiveness.-The bactericidal effectiveness of themixture of Compound A and Compound B of this Example is demonstrated bythe following Table in which the inhibiting power of a 50/50 by weightmixture of A and B is shown. Aerobacter aerogenes was employed as thetest organism and a substrate technique was utilized. Specifically, thebiocidal mixture was added in gradually increasing quantities tonutrient agar media which was then inoculated with A. aerogenes. Thepreparation was then incubated for 48 hours. The values set forth in theTable indicate the quantity of biocide required, in parts by weight foreach one million parts by weight of the medium, in order to achievecomplete inhibition of the growth of the test organism.

TABLE 1A Quantity (p.p.m.) required for inhibition Biocidal material: ofA. aerogenes Compound A (50%), Compound B (5% Inert 300 Fungicidaletfectiveness.-In order to test the effectiveness of the inventivemixtures in respect to fungi, evaluations were made following theprocedures described by B. F. Shema and I. H. Conkey [Journal for TheTechnical Association of The Pulp and Paper Industry, 36, 20A30A(1953)]. The described procedure generally entails incorporating thebiocide under test in a nutrient substrate such as agar, malt, etc. andpouring the resulting medium into a Petri dish and allowing the mediumto solidify. A button of fungus inoculum is placed on the surface of thesolidified medium and the medium is incubated for a period of 14 days.After the period, the diameter of the colony is measured and comparedwith the diameter of the button of inoculum originally placed TABLE 1BQuantity (p.p.m.) for inhibition Biocidal material Compound A (5%),Compound B (5%),

inert (90%) Slime control effectiveness-The inventive methods andcompositions were also tested with respect to their performance in thecontrol of slime formation in industrial systems. In this test anindustrial recirculating water was obtained from a system which wascurrently experiencing problems in respect to the formation of slime bymicroorganisms. Such tests do not demonstrate the efiiciency of thebiocide employed with respect to specific species of microorganisms butinstead supply a practical demonstration of the eflicacy of the biocidetested in relation to those communities of microorganisms which haveevidenced their ability to form slime in actual industrial systems. I

In the testing of recirculating water samples, a substrate evaluationwas employed. In such testing identical portions of water samples aretreated with varying concentrations of biocide and two portions are leftuntreated to serve as controls. The control portions are plated fortotal count at the beginning of biocide treatment and all portions areplated for total count at some suitable time period(s) after beginningbiocide treatment. Using the counts obtained from the plating, thepercentage kill (based on the initial control count) may be calculated.In this evaluation the water sample was taken from a water tray of apaper machine located in the northeastern United States.

For the purposes of comparison, the mixture of A and B was evaluatedtogether with two recognized commercial A perusal of the recordedpercentages clearly establishes that the composition of the presentinvention, although less concentrated with respect to active ingredientsas compared to the two commercial products, gave excellent rates of killeven at low treatment levels. As earlier ex pressed, excellentperformance of a biocidal composition at low treatment levels not onlyprovides a most desirable cost performance index, but also provides mostdesirable advantages from the aspects of pollution abatement, wastetreatment costs and the preservation of the ecological strain.

P. expansum A. Man

Example 2 Synergistic combination:

Compound A: 5-chloro-4-phenyl-1,2-dithiole-3-one Compound B:Ortho-phenylphenol The compositions of this Example contained5-chloro-4- phenyl-1,2-dithiole-3-one (referred to as Compound [A in theTest Equations and in Tables 2 through 2C) and ortho-phenylphenol(referred to as Compound B in this Example). The compositions of thisExample were tested in accordance with the test procedures outlined inExample 1. The data ascertained for the respective tests are recordedbelow under the commensurate Table.

Synerigstic Index Test.For mixtures of Compounds A and B, and forCompound A and Compound B acting alone, the following results wereobserved:

The above evaluation established that the compositions in the weightratios evaluated all exhibited synergistic activity. As set forth in theexplanation of the test earlier in this text, when is less than 1, thenthe two individual components are acting in a synergistic manner.

Bactericidal effectiveness.-The bactericidal effectiveness of thecombination of this Example was tested in accordance with the procedureoutlined in Example 1. The values obtained are recorded in Table 2Awhich follows:

TABLE 2A Quantity (p.p.m.) required for inhibition of Biocidal MaterialA. aerogenes Compound A (5% Compound B (5%), Inert The above dataestablished that the combination effectively inhibited the growth of theparticular bacterial strain.

Fungicidal effectiveness.-The eifectiveness of the composition ofExample 2 was tested in accordance with the procedures set forth inExample 1. The results were:

TABLE 2B Quantity (p.pm.) for inhibition Biocidal material P. upamum A.niger Compound A (5%), Compound B(5%),

inert (90%) 500 500 TABLE 2C Quantity Percent of biocide kill afterBiocidal material (p.p.m.) 6 hours Compound A (5%), Compound B (5%),inert (90%)- 5 Do 10 12 Do 25 35 Do 50 95 D0 100 100 Pentachlorophenol(100%). 41 D0 59 D0 87 D0 50 100 D0 100 100 Commercial product act1veSeeTable 10) 13 g 25 0 50 18 100 28 The results obtained for the inventivecomposition were comparable to the pentachlorophenol at high treatmentdosage and were overall superior to the Commercial Product which hasfound widespread acceptance and use. Moreover, when the lowconcentrations of the active ingredients are considered, it is obviousthat the inventive composition was quite active in kill percentage.

Example 3 Synergistic combination:

Compound A: 5-chloro-4-phenyl-l,2-dithiole-3-one Compound B:2-chloro-4-phenylphenol TAB LE 3 Quantities producing end points(p.p.m.) QA QB Weight ratio l of A to B QB Mixture QA/Qn QB/Qb Qu Qb Theresults obtained for this particular combination establishedunequivocally that the two ingredients behave synergistically together.

Bactericidal etfectiveness.The test procedure as described in Example 1was utilized. The results established that the composition was efiectivein controlling this strain of bacteria.

TABLE 3A Quantity (p.p.m.) required for inhibition Biocidal material: ofA. aerogenes Compound A (5% Compound B (5 Inert Fungicidalefiectiveness-The fungicidal activity of the composition of this Examplewas tested in accordance with the procedure previously described. Theresults were:

TABLE 3B Quantity (p.p.m.) for inhibition Biocidal material Compound A(57), Compound B 5 inert 90% .f'

P. ezpansum A. niger Slime control eifectiveness.The slime controleffectiveness of the present composition was evaluated using actualpaper mill water as explained under the procedure outlined in Example 1.As with the previous Examples, the composition was compared withcommercially available products using samples of water derived from thesump of an airwasher of an industrial cooling water system located inthe northeastern United States.

TABLE 30 Quantity Percent of bioclde kill after Biocidal material(p.p.m.) 6 hours Compound A (5%), Compound B (5%), inert Again, theslime control eifectiveness of the instant composition even at onlythree hour contact times was superior to the commercial products at lowtreatment ranges and was significantly better overall as compared to the30% active Commercial Product.

Example 4 Synergistic combination:

Compound A: 5-chloro-4-phenyl-1,2-dithiole-3-one Compound B:2,3,4,6-tetrachlorophenol Synergistic Index Test.--The synergisticactivity of the combinations of 5-chloro-4-phenyl-1,2 dithiole-3-one(referred to as Compound A) and 2,3,4,6-tetrachlorophenol (referred toin this Example as Compound B) was evaluated in accordance with the testdescribed. The results were as follows:

For mixtures of Compounds A and B, and for Compound A and Compound Bacting alone, the following results were observed:

of less than 1 which, of course, established that the individualingredients operated in concert to produce a synergistic result.

Bactericidal effectiveness-The efiicacy of the compositions of thisExample was tested in accordance with the procedure outlined earlier.The results of the test clearly established that the combination of theinstant invention is eflective even at low percentages of activeingredients.

TABLE 4A Quantity (p.p.m.) required for inhibition Biocidal material: ofA. aevrogenes Compound A (5%), Compound B (5% Inert 9 Fungicidaleifectiveness.--'Ihe fungicidal activity of the composition of thisExample was tested in accordance with the procedure previouslydescribed. The result of this evaluation was as follows:

TABLE 413 Quantity (p.p.m.) for inhibition Biocidal material P. ezpamumA. niger Compound A (5%), Compound 13 (5%),

inert (90%) 100 500 Slime control elTectiveness.As in the previousExamples and in the manner set forth in the previous Examples, the slimecontrol elfectiveness of the composition of the Example was tested. Theoutcome of this evaluation and the data derived using the CommercialProducts are set forth in the following Table. The water sample used inthis test was obtained from the airwasher sump of a cooling towerlocated in the northeastern United States.

The composition of this Example, as with the previous Examples,exhibited overall desirable and attractive slime control capacity. Ofspecial interest is the fact that at low percentage activeconcentrations the compositions were capable of controlling theslime-forming organisms.

Example 5 Synergistic combination:

Compound A: 5-chloro-4-phenyl-1,2-dithiole-3-one Compound B:4-chloro-2-cyclopentylphenol TABLE 5 Quantities producing end points(p.p.m.) QA Q Weight ratio otA to B QA QB Mixtur Q /Qn QB/Qb Qa Qb Allof the combinations tested exhibited a QA QB aim of less than 1 which,of course, established that the individual ingredients operated inconcert to produce a synergistic result.

Bactericidal effectiveness.The efficacy of the compositions of thisExample was tested in accordance with the procedure outlined earlier.The results of the test clearly established that the combination of theinstant invention is effective even at low percentages of activeingredients.

TABLE 5A Quantity (p.p.m.) required for inhibition Biocidal Material ofA. aerogenes Compound A (5%), Compound B (5%), In-

ert 300 Fungicidal eifeetiveness.The fungicidal activity of thecomposition of this Example was tested in accordance with the procedurepreviously described. The result of this evaluation was as follows:

TABLE 5B Quantity (p.p.m.) for inhibition Biocidal material Compound A(5%), Comp n B inert (90%) P. expansu'm A. niger TABLE 50 QuanityPercent Biocidal of bioeide kill after material (p.p.m.) 6 hoursCompound A (5%), Compound B (5%) inert (90%) 5 38 Do 10 84 Do 25 86 Do50 92 Do 100 95 Pentachlorophenol 5 89 D o 10 94 Do 25 100 Do 50 100 D100 100 5 38 10 36 25 9 50 0 100 36 The composition of this Exampleexhibited overall desirable and attractive slime control capacity. Ofspecial interest is the fact that at lower percentage activeconcentrations the compositions were capable of controlling theslime-forming organisms.

When the inventive compositions are employed in the treatment of coolingor paper mill water, they are preferably utilized in the form ofrelatively dilute solutions or dispersions. For example, a preferredsolution comprises between 5% to 65% by weight of the synergisticcombination in admixture with various solvents and solubilizing agents.An example of such a synergistic biocidal product comprises from about 5to 10% by weight of the phenol, from about 5 to 10% by weight of the5-chloro-4-phenyl-l,2-dithiole-3-one and the remainder composed of suchmaterials as surfactants, stabilizers, organic solvents, such asalkanols, aromatic hydrocarbons and/ or Water.

Surfactants such as the alkylaryl polyether alcohols, polyetheralcohols, sulfonates and sulfates, and the like, may be employed toenhance the dispersibility and stability of these dispersions. Theforegoing solutions of the biocidal compositions are utilized in orderto insure the rapid and uniform dispersibility of the biocides withinthe industrial water which is treated. It has been found that eitheraqueous or non-aqueous solvents are generally suitable in thepreparation of compositions of the invention, e.g., methyl Cellosolve,organic solvents such as the aliphatic and aromatic hydrocarbons, e.g.kerosene. Based upon the synergism study as outlined above, it wasascertained that in the treatment of paper mill and cooling water,efi'ective biocidal action is obtained when the concentration ortreatment level of the combination or admixture of biocides is between0.5 parts per million to 1000 parts per million, and preferably between1 and 100 parts per million, based upon the total content of the aqueoussystem treated, such as the total quantity of cooling water or papermill water.

The compositions may also be utilized for the preservation of slurriesand emulsions containing carbohydrates, proteins, fats, oils, etc.;dosage levels for this purpose range in the vicinity of 0.01 to 5%. Thecompositions of the invention which can be prepared by merely combiningthe respective ingredients and mixing thoroughly at standard conditionsmay be fed continuously to the treated system, e.g., by means of ametered pump, or may be fed periodically at predetermined intervalscalculated to control the growth of slime-forming organisms in thesystem. Naturally, in the treatment of cooling water, the feeding of theinventive compositions must be designed to compensate for blowdown inthose systems which employ that expedient.

Although the foregoing has been specifically directed to liquidformulations, the combinations of the invention may, of course, beformulated dry with well-known pelletizing agents, e.g. sodium chloride,talc, aluminate, etc. to produce solid pellets or briquettes which areadded directly to the systems to be treated. The pellets or briquettes,of course, dissolve in accordance with predetermined conditions orrates.

In describing the inventive subject matter, the expression compositionhas been utilized. However, it is to be understood that physicalcompositions or combinations are not the sole utility of the invention.If, for example, the separate ingredients of the composition are addedindependently to a particular system, it is intended that this usage ofthe subject matter is within the scope of the invention and is to beconstrued within the broad interpretation of composition and/orcombination.

As would be expected, the inventive composition may be added to thecooling water or paper and pulp mill systems at any convenient point.Naturally, in oncethrough or non-circulating systems, the compositionsmust be added upstream from the point or points at which microorganismcontrol is desired. In circulating systems or pulp and paper systems,the compositions must be added at any point provided that the time lapseand the conditions experienced between point of addition and the pointat which the elfect of the composition is to be experienced are not sodrastic as to result in the neutralization of the effect of thecomposition.

Although the invention has been described specifically as being directedto specific compositions comprising 5-chloro-4-phenyl-1,2-dithiole-3-one in combination with the phenol asdescribed in Example 1, the phenylphenol of Example 2, the2-chlorophenylphenol of Example 3, the chlorophenol of Example 4 or thepentylphenol of Example 5, it is obvious that homologues, analogues,etc. of the dithiole-B-one compound certainly are operable for thepurpose. Likewise, the derivatives of the specially exemplifiedorgano-bromine compounds also have utility in the present inventiveconcept.

It should be noted while the evidence has been derived from thetreatment of samples taken from paper and pulp mill aqueous systems, thecompositions and methods of the present invention are broadly applicableto the treatment of aesthetic waters as well as industrial waters suchas cooling waters which are plagued by deposits formed by slime-formingorganisms, or by the very presence of such organisms.

Having thus described the invention, what we claim is:

v1. A method for controlling the growth of slime-forming micro-organismsin an aqueous system which comprises adding to said system an effectiveamount of a combination comprising from about 5 to by weight of5-chloro-4-phenyl-1,2-dithiole-3-one and from 5 to 95 weight ofortho-phenylphenol.

2. A method according to claim 1 wherein the combination containsapproximately 50% by weight of each of said dithiole-3-one and saidphenol.

3. A method according to claim 1 wherein the combination is added tosaid system in an amount of from about 0.5 to about 1000 parts by weightof said combination per parts by weight of said aqueous system.

4. A method according to claim 3 wherein the combination is added tosaid system in an amount of 1 to parts per million parts of said aqueoussystem.

5. A method according to claim 3 wherein the aqueous system is theaqueous system of a cooling water system.

6. A method according to claim 3 wherein the system is the aqueoussystem of a pulp and paper mill system.

7. A slime control composition containing on a weight ratio bases fromabout 5 to 95% of 5-chloro-4-phenyl- 1,2-dithiole-3-one and from about 5to 95% of orthophenylphenol.

8. A composition according to claim 5 wherein the composition containsapproximately 50% by weight of each of said dithiole-3-one and saidphenol.

9. A composition according to claim 8 wherein the composition isdissolved in an appropriate hydrocarbon solvent.

References Cited UNITED STATES PATENTS 8/1961 Josephs 71-66 4/1962 Brack424-277 JAMES O. THOMAS, 111., Primary Examiner

